Building equipment for viewing 3-dimensional (volumetric and, in particular, stereo) representations is an entirely appealing and achievable task. Such equipment can have very wide application both in fields of science, in engineering development, in industrial production, in medicine, as well as in computer systems, advertising, show business, design, simulators and gaming equipment, and in movie and television technology. This last field is particularly attractive in view of its wide dispersion and societal demand. It is significant in this regard, that for effective and wide use of the technology of 3-dimensional (volumetric) TV, principles must be developed for construction not only of 3-dimensional display equipment, but also for suitable technology for transmitting equipment.
The capacity for 3-dimensional vision is inherent in humans. It is therefore natural that inventors have long sought methods and equipment for representation and display of 3-dimensional objects. More than 150 years ago studies were already being conducted on binocular vision and experience was gained in construction of stereoscopic devices (Charles Whearstone, Contributions to the physiology of vision.-Part the first. On some remarkable, and hitherto unobserved, phenomena of binocular vision. Philosophical Transactions of the Royal Society of London 1838). From that time, and especially recently, a great number of inventions have been registered in this field. These take many directions and employ different principles for construction of equipment and in their approach to the task. One of these directions is use of “auto-stereoscopic” methods and equipment using the “principles of 3-dimensional vision without glasses” (Selected Papers on Three-Dimensional Displays. Editor Stephen A. Benton. Introduction SPIE Milestone Series, Vol. MS 162, Stephen A. Benton. Autostereoscopy becomes holography: historical connections. Three-Dimensional Video and Display: Devices and Systems. Proceedings of a conference held. November 2000, Boston, Mass., pp. 154-167). There is also the possibility of reproduction of both static displays and moving scenes (objects).
In turn, within this direction it is possible to distinguish a few fundamental approaches. A number of systems have been built on the principle of the existence of special (discrete, fixed) spatial zones to which the right and left eyes of the viewer must be directed in order to realize a stereoscopic effect. In these systems there can be only two zones (U.S. Pat. No. 6,268,881, 2001) or more (U.S. Pat. No. 6,476,850, 2002, U.S. Pat. No. 6,533,420, 2003). However with these systems there continually arises the problem of tracking, that is, the necessity of fixing the position of the eyes (and head) of the viewer in order to direct vision to these zones. This is a major inconvenience and limits acceptance of such equipment.
One variant for solution of this problem is the use of various systems for automatic tracking of the position of the eyes (or head) of the viewer and alignment of the zones themselves, or the use of supplementary equipment to facilitate correction of the position of the viewer himself (U.S. Pat. No. 5,742,332, 1998, U.S. Pat. No. 5,712,732, 1998, U.S. Pat. No. 6,337,721, 2002, U.S. Pat. No. 5,930,037, 1999). Such systems, besides the necessity of employing a relatively complex tracking mechanism, are not intended for simultaneous use by multiple viewers.
There are a number of systems, also called “volumetric” displays, in which a volumetric (3-dimensional) representation is reproduced either using displacement of a 2-dimensional screen in the distance (U.S. Pat. No. 2,198,678, 1940) or its rotation with respect to the vertical axis (U.S. Pat. No. 4,160,973, 1979, U.S. Pat. No. 6,487,020, 2002), or using a large-scale multilayer display (U.S. Pat. No. 5,745,197, 1998), or by focusing illumination on a dispersing medium (U.S. Pat. No. 3,632,866, 1972) The main and most significant defect of such systems is that they do not facilitate a “shading effect” (Selected Papers on Three-Dimensional Displays. Editor Stephen A. Benton. Introduction. SPIE Milestone Series, Vol. MS 162). In addition, in those variants using mechanical displacement of screens (back-and-forth in the “distance” or rotational), producing systems with large screens is technologically unrealistic.
Systems are also known, in which matrices of spatial light modulators (SLMs) are joined to matrices of micro-lenses (or holographic optical elements) (U.S. Pat. No. 5,581,378, 1996). However, each element of the optical matrix must contain a large number of SLM elements (and each element of the optical matrix must be joined to a large number of STLM elements). Because of this, it is possible to show simultaneously the majority of aspects and to produce a representation of a 3-dimensional object. However the practical value of such a display can only be realized through the use of SLMs, which would require thousands of additional elements compared to SLMs developed at the present time. However, existing technology is still not sufficient for realization of these parameters.
There is also a system in which the aspects of 3-dimensional representation are shown sequentially using fast-moving SLMs, which for display of each aspect is illuminated at various (corresponding) angles (U.S. Pat. No. 5,132,839, 1992). The main, and at present unresolved, problem significantly limiting the practical use of this technical solution is the absence of STLMs capable of rapid movement and of sufficiently large dimensions (only systems the size of a micro-display exist).
The majority of stereo (3-dimensional) displays described above can also be used to show stereo TV programs, but with significant limitations, which are the result of the defects mentioned above. In addition, these systems lack corresponding systems for display and transmission of stereo representation of 3-dimensional objects.
However, there is a system for 3-dimensional television that includes both a 3-dimensional display and a working system for display and transmission of stereo representation of 3-dimensional objects. Based on a series of significant indicators, this patent is closest to the proposed invention and is taken as a prototype (U.S. Pat. No. 3,932,699, 1976).
In this system the illumination (light) from the 3-dimensional scene is directed, using a converging lens (objective), to a matrix of micro-lenses and, passing through the matrix, it strikes a photo-detection system (television transmitting camera). The matrix of micro-lenses, in this case, is a lenticular array, consisting of a large number of vertically aligned cylindrical lenses. Such a matrix discriminates (spatially) the illumination from various aspects of the object and brings into focus each element of the representation of various aspects on various corresponding parts in the plane of focus in which is located the photo-detection surface (the transmitting television camera). In this way, all possible representations of the aspects of a 3-dimensional object in this optical system, digitized and spatially arranged in relation to each other, are simultaneously projected on the photo-detection equipment. Electrical signals, corresponding to the location of various elements of the representation of the aspects, are received in the photo-detection equipment as usual and are transmitted through a communications channel to the receiving equipment—a 3-dimensional stereo display. The 3-dimensional stereo display, including a normal (2-dimensional) TV display (monitor), reproduces elements of the representation's aspects. Then the illumination from these elements passes to a different matrix of micro-lenses on the surface of the monitor, and then to a different matrix of micro-lenses in the transmitting equipment. Elements of the matrix used in the display are arranged in a similar manner with respect to the picture reproduced by the monitor and direct their illumination to the viewer at various angles corresponding to the various aspects of the 3-dimensional object (scene).
Regarding a system using a component for producing a stereoscopic representation, this well-known technical solution (U.S. Pat. No. 3,932,699, 1976) can also be seen as a prototype.
This prototype has the following defects:
Both the photo-detecting transmitting camera and the display monitor require a large number of elements (a large computing capacity) in order to display a sufficiently high-quality 3-dimensional representation at acceptable viewing angles, that is, to provide comfortable conditions for viewers. Thus, at the usual resolution for TV (no less than 500 elements per line) in order to present a 3-dimensional representation with acceptably high quality at an angle of about 20 degrees, the camera and, correspondingly, the monitor, must contain more than 50,000 horizontal elements, which is unrealistic given the present state of technology in this field.
To provide a quality reproduction of a volumetric stereo representation on a 3-dimensional display, it is necessary that the elements comprising the 2-dimensional component of the display be very precisely placed with respect to the elements of the micro-lens matrix, which is a complex technological problem considering the unavoidable distortion of images (mainly of scale) in present-day equipment.
The task of the invention is the design of equipment for transmission and display of representations of 3-dimensional objects (scenes), both static and moving, which provides comfortable viewing conditions (perception): which, in order to produce the desired perception, does not require the use by the viewer of either supplementary means such as special glasses or tracking devices, which does not drastically constrain the position of the viewer with respect to the display, and which facilitates viewing of the 3-dimensional representation simultaneously by multiple viewers in a sufficiently wide field of view. In addition, such equipment must be scalable—it must be possible to manufacture displays (screens) of both small and large (for a large number of viewers) dimensions, and they must use simple and complex components that are presently in production and available. It is also important to minimize the dimensions and mass of the equipment.